Method of deodorizing a hydrocarbon liquid



April 23, 1935. A. E. DUNSTAN METHOD OF DEODORIZING A HYDROCARBON LIQUID Filed Sept. 18, 1951 Inventor .4. aa mwmfl Attorney.

Patented Apr. 23, 1935 UNITED STATES METHOD OF DEODORIZING A HYDRO- CARBQN LIQUID Albert Ernest Dunstan, London, England, as-

signor to' Anglo-Persian Gil Company Limited,

London, England Application September 18,

Great Britain March 4, 1931 Claims.

This invention relates to the refining of hydrocarbon liquids and especially of petroleum distillates. I

The invention has among its objects to avoid I certain practical disadvantages in the use of chlorine or of'chlorine compounds such as sodium hypochlorite in the refining of petroleum distillates, for the removal of sulphur compounds and odour.

According to the invention a reagent adapted to effect the selective partial oxidation of the sulphur content of the hydrocarbon liquid, and to leave a substantially inodorous sulphur content is used in a highly dilute solution ofgconsiderable volume, such, for example, as 50% by volume of the total mixture of reagent and hydrocarbon liquid, and the treatment of the hydrocarbon liquid is carried out by repeated washing with the large volume of solution and by prolonged contact, involving intimate admix ture of the hydrocarbon liquid with the solution in a plant in which the hydrocarbon liquid and the washing solution flow in counter-current. For this purpose a highly dilute and slightly a1- kaline solution of used in the proportion,.ior example of 0.07 normal hypochlorite and 0.04 normal alkali. The treatment aims at the substantially complete elimination of unpleasing odour by the selective partial oxidation of the sulphur content in the treated oil.

By reason or" the use of the reagent in a highly dilute solution of considerable volume and the repeated and intimate admixture of the solution with the hydrocarbon liquid treated, the development of acidity and chlorination are avoided. The ultimate reversion of colour and smell in the treated hydrocarbon liquid as well as loss of resistance to detonation in. the use of the treated hydrocarbon liquid as a motor fuel, are also avoided.

The extent of dilution of the reagent used according to the invention is considerably greater than that usual in batch washing, where a dilution comparable to that used according to the invention would render the treatment impracticable by reason of the enormous volume of the washing liquor that would be required. Similarly the extent of dilution of the reagent used according to the invention is also considerably greater than that hitherto used in'counter-current washing of hydrocarbon liquids. The high degree of dilution may however vary according to the character of the hydrocarbon liquid to be sweetened or deodorized.

repeated washing of sodium hypochlorite may be 1931, Serial No. 563,638

The invention comprises the conditions of the treatment in the examples hereinafter referred to.

In carrying the invention into effect the treatment may advantageously be carried out in a 5 plant such as described in the specification of the co-pending application Serial No. 373,047by a hydrocarbon liquid successively with various reagents which flow through the units of the plant in counter-curl0 rent with the hydrocarbon liquid to be treated. The invention may however be carried out in any other plant in which the hydrocarbon liquid may be repeatedly washed under conditions of intimate admixture of the hydrocarbon liquid with large volumes of solutions of the respective reagents to be employed, and in which the hydrocarbon liquid and the washing solutions flow in counter-current. l

Plant suitable for carrying out the treatment according to the invention is diagrammatically indicated in the accompanying drawing, in which four pairs of mixing vessels and separating vessel a b are indicated through which the highly dilute I washing solution successively passes in 5 counter-current with the hydrocarbon liquid to be treated.

In carrying the invention into effect in the treatment of a straight benzine derived from a sulphur containing crude oil, having a content of .l% or over of sulphides, mercaptans, disulphides and other sulphur compounds, certain of these bodies or their derivatives require elimination, while othe'rs'require change by oxidation into inodorous and stable derivatives. For this purpose the benzine may be subjectto a preliminary wash with alkali for the removal of hydrogen sulphide, and for the partial removal of mercaptans low in molecular weight. The benzine may then be washed with a highly dilute solution 40 of sodium hypochlorite containing free alkali, in the proportion for example of 0.07 normal hypochlorite and 0.0% normal alkali, in a counter-current washing plant such as hereinbeiore described, whereby the remaining m'ercaptans and the lower sulphides are oxidized. The treated benzine may then be washed by weak alkali in a series or" counter-current stages in one or more pairs of mixing and separatingvessels such as hereinbefore described, whereby the traces of acidic bodies are removed, that are responsible for ultimate reversion of colour and smell. By such means the sulphur content may be reduced below .l% and a non-reverting spirit of good odour and colour produced.

In carrying the invention into effect in the treatment of a pressure distillate produced in a cracking distillation in the liquid phase, the gum forming bodies may be removed by known treatment, such for example as by treatment with sulphuric acid followed by re-distillation, while the distillate may then be sweetened by a treatment such as hereinbefore described, comprising a preliminary washing with alkali, followed by a washing with a highly dilute solution of a hypochlorite in a counter-current washing plant such as hereinbefore described, and with a final washing with alkali. Thus the pressure distillate may be similarly washed in countercurrent with by volume of sulphuric acid after which it may be re-distilled. The distillate may be similarly washed in counter-current with 8% by volume of normal sodium hypochlorite appl ed in a dilution of .97 normal and alkali .94 normal, after first being similarly washed in counter-current with weak alkali solution and finally again washed with weak alkali solution.

Cracked spirit produced in a vapour phase cracking treatment may be similarly treated, whereby a perfectly stable product may be produced under similar conditions, the concentration of the alkaline hypochlorite remaining the same, but the quantities of the reagents and duration of the treatment will depend upon the nature of the original crude oil from which the distillate is derived and the degree of refining desired. In ti e treatment of cracked spirit the aim of the treatment is to produce a water white liquid of good odour having a low gum test (e. g. 5 milligrams of gum per 100 cc.) with freedom from reversion both in colour and smell.

The invention may similarly be carried into efiect in the treatment of a light kerosene having a high aromatic content and a substantial proportion of sulphur, such as may be derived from the S02 extract produced in the treatment of kerosene with liquid sulphur dioxide. Such a light kerosene may be treated in counter-current washing with a reagent in highly dilute solution in the manner hereinbefore described for sweetening and for the oxidation of the mercaptans, without complete removal of the sulphur content, and the acidity may then be removed by counter-current washing with alkali in the manner hereinbefore described.

The vessels of the plant employed for the counter-current washing treatment are preferably closed and fitted with hinged explosion covers, the movement of which may be restricted by means of a metal frame whereby the covers may thus return to the closed position after their outward movement. Such mixing vessels as as illustrated in the accompanying drawing are provided with means such as rotating vanes h for intimately mixing a highly dilute aqueous solution of chlorine or chlorine compound such as sodium hypochlorite, with the less dense hydrocarbon liquid. The pipe connections between the respective mixing and separating vessels a b are such that the less dense hydrocarbon liquid may pass from a supply tank y to the mixing vessel a at one end of the series, and the highly dilute Washing solution may pass from a supply tank a to the mixing vessel a at the other end of the series, and the respective denser and less dense liquids flow in counter-currentthrough the respective pairs of vessels in series. The hydrocarbon liquid from any separating vessel b passes in one direction near the top through a pipe 1 into the mixing vessel a of the pair of vessels a b denser to the less dense liquids in next in the series, and the washing solution from that separating vessel passes in opposite direction near the bottom to the mixing vessel a of the pair of vessels at 22 next in series through a pipe 9. Each pair of the vessels 0: b are connected together at or about the middle of. the respective columns by a communicating pipe or pipes c2, and near their lower ends by a return pipe or pipes e, a valve being conveniently provided on the return pipes to maintain any desired ratio of the the mixing vessels a irrespective of the rates at which the respective liquids are fed to the plant, so that a part of the denser or washing liquid that passes into the separating vessel 0 is returned to the mixing vessel a whence it came, any desired part of the denser or washing liquid being meanwhile drawn off continuously into the next mixing vessel a of the series. The washing solution may be discharged through the outlet pipe 2 at the lower part of the'separating vessel 1; at the end i the series of vessels opposite that at which the supply tank a is placed, and the treated hya 'bon liquid may be discharged through the outl t pipe 3, at the upper part of the separating Co c vessel 32 at the other end of the series. ntrolling valves are advantageously provided on all the pipes throughwhich the liquids from supply tanks and through the respective e ls, as well as on the return pipes 6 between vessels of each pair. By such means the of iiow or" the respective liquids may be varied irrespective of the proportions maintained in the mixing and separating vessels. A high proportion of the washing liquid to the hydrocarbon liquid is advantageously maintained in the mixing and separating vessels. A high rate of throughput of the washing liquid through the plant is also advantageously imposed. Thus ior example the liquid to the washing liquid in the separating and mixing vessels may be approximately 5%):58, and the respective rates of feeding of the hydrocarbons and V]: liquids may respectively be 569 volumes per hour, but no limitation is involvecl to the widely variable conditions in the proportions of the liquids within the vessels or their rates of'flow through the plant. It will be understood that the counter-current flow of the liquids through the plant is caused solely by the head in the respective separating essels consequent upon the admixture of the liquids in the mixing vessels.

. It will be understood that the invention is no limited to the examples hereinbeiore described in which the invention is carried into effect, nor yet to use of the plant illustrated and hereinbeiore described. The preliminary, final and other treatments to which the hydrocarbon liquid is subjected maybe carried out the units of the same counter-current washing plant as that which the treatment for selective partial oxidation of the sulphur content in the hydrocarbon liquid is carried out according to the invention.

I claim:

of the hydrocarbon liquid and. to leave a substantially inodorous sulphur content, the washing being efiected by prolonged and intimate contact of the hydrocarbon liquid with a considerable volume of the volume ratio of the hydrocarbon I reagent in a highly dilute solution having a concentration such as 0.07 normal hypochlorite and 0.0% normal alkali.

2. A method of deodorizing a hydrocarbon liquid according to claim 1, wherein the washing with the reagent adapted to effect the selective partial oxidation of the sulphur content of the hydrocarbon liquid is effected by counter-current washing in a numberof stages.

3. A method of deodoriaing hydrocarbon liquids according to claim 1, wherein the washing with the reagent is eitected with a high rate of throughput.

4. A method of deodcrizing a hydrocarbon liquid in the liquid phase to effect the selective partial oxidation of the sulphur content of the hydrocarbon liquid without the complete removal of the sulphur and to leave a substantially inodorous sulphur content in the hydrocarbon liquid which comprises treating with prolonged and intimate contact the said hydrocarbon liquid with a considerable volume of a reagent comprising available chlorine in a highly dilute aqueous solution, the concentration of which does not substantially exceed .67 normal, the said hydrocarbon liquid being treated therewith sufficiently to leave a substantially inodorous sulphur content in the said hydrocarbon liquid.

5. A method of deodorizing a hydrocarbon liquid in the liquid phase to effect the selective partial oxidation of the sulphur content of the hydrocarbon liquid without the complete removal of the sulphur and to leave a substantially inodorous sulphur content in the hydrocarbon liquid which comprises washing countercurrently the hydrocarbon liquid with prolonged and intimate contact with a. considerable volume of a highly dilute aqueous solution containing a hypochlorite the concentration of which does not substantially exceed .6? normal, the said hydrocarbon liquid being treated suihciently with said solution to leave a substantially inodorous sulphur content in said hydrocarbon liquid.

6. A method of deodorizing a hydrocarbon liquid in the liquid phase to effect the selective partial oxidation of the sulphur content of the hydrocarbon liquid without the complete removal oi the sulphur and to leave a substantially incdorous sulphur content in the hydrocarbon liquid which comprises treating countercurrently with prolonged and intimate contact the said hydrocarbon liquid with a considerable volume of a reagent comprising available chlorine in a highly dilute and slightly alkaline aqueous solution in which the concentration of the said reagent does not ubstantially exceed .07 normal, the said hydrocarbon liquid being treated there'- with sufficiently to leave a substantially inodorous sulphur content inthe said hydrocarbon liquid.

7. A method of deodorizing a hydrocarbon liquid in the liquid phase toeflect the selective partial oxidation of the sulphur content of the hydrocarbon liquid without the complete removal of the sulphur and to leave a substantially inodorous sulphur content in the hydrocarbon liquid which comprises subjecting the said hydrocarbon liquid to a preliminary wash with alkali and thereafter washing the hydrocarbon liquid with prolonged and intimate content and in countercurrent relation with a considerable volume oi" a highly dilute aqueous solution of a reagent comprising available chlorine, the concentration of which does not substantially exceed .07 normal, the said hydrocarbon liquid being treated sufficiently with the said solution to leave a substantially inodorous sulphur content in the said hydrocarbon liquid.

8. A method of deodorizing a hydrocarbon liquid in the liquid phase to efiect the selective partial oxidation of the sulphur content of the hydrocarbon liquid without the complete removal of the sulphur and to leave a substantially inodorous sulphur cotent in the hydrocarbon liquid which comprises treating countercurrently with prolonged and intimate contact the said hydrocarbon liquid with a considerable volume of chlorine in a highly dilute aqueous solution in which the concentration of the said chlorine does not substantially exceed .07 normal, the said hydrocarbon liquid being treated therewith sufficiently to leave a substantially inordorous .sulphur content in the said hydrocarbon liquid.

9. A method of deodorizing a hydrocarbon liquid in the liquid phase to effect the selective partial oxidation of the sulphur content of the hydrocarbon liquid without the complete removal of the sulphur and to leave a substantially inodorous sulphur content in the hydrocarbon liquid which comprises treating countercurrently with prolonged and intimate contact the said hydrocarbon liquid with a considerable volume 01: a highly dilute aqueous solution of a chlorine compound having available chlorine'the concentration of which does not substantially exceed .07 normal, the said hydrocarbon liquid being treated therewith sufficiently to leave a substantially inodorous sulphur content in the said hydrocarbon liquid.

. 10. A method of deodorizing a hydrocarbon liquid-in the liquid phase to effect the selective partial oxidation of the sulphur content of the hydrocarbon liquid without the complete removal of the sulphur and to leave a substantially inodorous sulphur content in the hydrocarbon liquid which comprises washing countercurrently with prolonged and intimate contact the said hydrocarbon liquid with a considerable volume of a highly dilute and slightly alkaline solution containing a reagent having available chlorine, the concentration of the said chlorine reagent being not substantially above .67 normal and in a volume of said highly dilute solution or substantially 50% of the total volume of the mixture of solution and hydrocarbon liquid, the said hydrocarbon liquid being treated with said solution sulficiently. to leave a substantially inodorous sulphur content in the said hydrocarbon liquid.

' ALBERT E. DUNSTAN. 

